[ros-kernel] Mapping of page table

[Vizzini]

On Fri, 2003-11-07 at 15:45, Eric Kohl wrote:
> "Vizzini" <vizzini at plasmic.com> wrote:
> 
> 
> > I'd also like to discuss moving the kernel/hal back down to 0x80000000
> > while we're discussing this.  Forcing /3GB has the effect of depriving
> > the cache manager of virtual memory, which on big configurations may be
> > a bad thing.  What does everyone else think?
> 
> I think that's a good idea. AFAIR, Sven Schreiber wrote in his book
> 'Undocumented Windows 2000 Secrets' that the layout looks like this:
> 
>   0x80000000 - 0x8000FFFF (64KB) Mapped IVT, BIOS data, etc.
>   0x80010000 - 0x800FFFFF Hal
>   0x80100000              Ntoskrnl
> 
> I think mapping the lowest 64k of real mode memory (IVT, BIOS data, etc)
> into kernel space could be useful for BIOS calls, especially for the VGA
> driver.

David, if you're out there, or anyone else, can you comment on why this
design decision was made?  I think /3GB support is a good idea, but why
not duplicate the default win2k virtual address space layout and support
a /3GB switch too?

As for apps that need big memory, does anyone know if many apps still
depend on this mechanism?  I was under the impression that software
architecture was moving away from /3GB and towards PAE.

 -Viz